CONTENTS 



PAGE 



PREFACE v 



SUGGESTIONS TO TEACHERS xi 



CHAPTER I. THE FUNDAMENTAL RELATION BETWEEN FLUX AND MAG- 

 NETOMOTIVE FORCE 1 



A simple magnetic circuit. Magnetomotive force. Magnetic flux. 

 The reluctance of a magnetic path. The permeance of a magnetic 

 path. Reluctivity and permeability. Magnetic intensity. Flux 

 density. Reluctances and permeances in series and in parallel. 



CHAPTER II. THE MAGNETIC CIRCUIT WITH IRON 20 



The difference between iron and non-magnetic materials. Mag- 

 netization curves. Permeability and saturation. Problems involv- 

 ing the use of magnetization curves. 



( 'H.MTER III. HYSTERESIS AND EDDY CURRENTS IN IRON 32 



The hysteresis loop. An explanation of saturation and hysteresis 

 in iron. The loss of energy per cycle of magnetization. Eddy cur- 

 - in iron. The significance of iron loss in electrical machinery. 

 The total core loss. Practical data on hysteresis loss. Eddy cur- 

 rent loss in iron. The separation of hysteresis from eddy currents. 



( 'II.MTER IV. INDUCED E.M.F. IN ELECTRICAL MACHINERY 55 



Methods of inducing e.m.f. The formulae for induced o.m.f. 

 The induced e.m.f. in a transformer. The induced r.m.f. in an 

 alternator and in an induction motor. The breadth factor. The 

 slot factor k t . Tho winding-pitch factor k*. Non-sinusoidal vol- 

 tages. The induced e.m.f. in a direct-current machine. Tue ratio 

 of A.C. to D.C. voltage in a rotary converter. 



< II MTEB V. EXCTTINO AllPKRE-TURNB TO ELECTRICAL MACHINERY 80 



The exritinr nirrmt in .1 transformer. The exciting current in i 

 transformer with a saturated core. The types of magncti. , 

 occurring in revolving machinery. The air-gap ampere-turns. The 

 method of equivalent permeances for the calculation of air-gap 

 ampere-turns. 



vii 



